Driving an electric vehicle (EV) has obvious climate benefits: zero tailpipe emissions. But because EVs are charged by power grids that burn fossil fuels, they aren’t necessarily zero-carbon. An EV’s carbon footprint depends on whether its power comes from renewables or fossil, and quantifying exactly how clean EVs are compared to gasoline-powered vehicles has been tough – until now.

Average EV emissions have continued to decline over time thanks to accelerating coal plant closures and the decarbonization of America’s power sector (down 28% since 2007), so while burning gasoline won’t get much cleaner, driving on electricity can get cleaner every year – saving billions in health expenses and climate impacts along the way.

UCS finds driving on electricity is far cleaner than gasoline – charging up an EV equals 50 MPG for 75% of U.S. drivers, and it’s much higher in regions where clean power composes a significant portion of the power mix: 102 MPG in New England, 109 MPG in California, and a whopping 191 MPG in New York State. UCS also provides comparative emissions data down to the zip code via their online calculator – for instance in my Oakland, California zip code the average new car powered only by gasoline gets 29 MPG compared to 114 MPG for an EV.

This difference between gas-powered cars and EVs is important to U.S. climate change concerns. A typical gas-powered car emits around a pound of carbon dioxide per mile traveled, and the U.S. reached an all-time high of 3.17 trillion annual vehicle miles traveled in 2016. As a result, transportation sector emissions supplanted power plant emissions as America’s top source of emissions for the first time in 2016, while electricity emissions continued a decade-long decline.

Tailpipe emissions also carry a hefty human health price tag: The American Lung Association says gasoline-powered transportation costs $37 billion in hidden impacts like asthma attacks, premature deaths, lost work days, and hospital visits across just 10 states. Since Americans won’t stop driving cars any time soon, the cars on our roads must be as clean as possible – to get serious about cutting emissions, we must rapidly electrify transportation.

EV Sales Increasing In Time to Tap Cleaner U.S. Electricity

EV sales are rising in the U.S. just in time to capitalize on the influx of cheap and clean generation coming online across the country. EV prices are falling rapidly, and many analysts project they will soon overtake gas-powered engines as the primary source of new car sales in America.

These rapid market expansions are happening due to rapid technology cost declines – lithium-ion battery prices have fallen 73% since 2010 and could decline another 70% by 2030, pushing EVs to price parity with gas-powered cars by 2025.